The riverundi split off from its ancestor the scavengundi. It now has an amphibious lifestyle living in and on the banks of the Flisch river, lake and marsh. They have evolved webbed membranes between part of their legs which allows them to swim. They also evolved an extra toe on their hind legs to help in this, making the back web feed larger for swimming. They, as a colony, will gather up mud and floral matter to build a huge colonial dam. The colony consists of hundreds of individuals, with one queen, a few soldiers (which are all male) for mating and guiding entrances to the colony and the rest workers (who are all female) who collect and build the colony as well as gather food and raise the young.
The queen spends her whole life mating and giving birth. If the queen dies a worker will take her place and grow much bigger as well as activate her reproductive organs. This is usually a worker who already helps the queen give birth. The workers are all females yet they are not fertile; this is because of the hormones in the queen’s urine-sweet. The soldiers on the other hand are all fertile males. Each week a group of chosen soldiers fight each other to death and the winner gets to mate with the queen. The queen gives birth every week to about 10 babies. They are altricial, and need much care from the workers. It's not until they are adults that they learn how to swim so they can gather food outside the colony.
The colony dam contains many chambers. Some are resting places for workers, others are for raising young, one is for the queen, and most are for storing food. These are all underwater except for the air holes in the top. This is so any would-be predators cannot get in. Their main food is marshrub and river shrub leaves. The colony will strip the leaves bare and use the stems and trunk as part of the colony. In return they will leave their dung around the plants to fertilize them, thus they never completely kill off a shrub after harvesting it. This is dormant behaviors left over from when their distant ancestor grew cropshrooms. They now use their puffy cheeks to store the leaves, and when they return to the colony they will split it out. Since they breathe through their rears they can hold it without having to hold their breath on land; however the butt-nostril is air tight when swimming in the water. They have also evolved a second, see through eye-lid so they can see while swimming. This eyelid is vertical rather than horizontal. Their ears now can seal water tight as well, which means they are deaf when underwater.
Their trunk has grown larger and the trunk horn of the soldiers is even sharper and deadlier. This is so they can cut off the leaves better. They can even cut off leaves while swimming. This comes in handy for the aquatic river shrub. Their squeaks are ultrasonic, and hence inaudible to larger animals; they however cannot communicate underwater. Their back legs have grown larger and stronger for swimming, giving them a waddling gait when on land. Their blue coloring is to blend in with the shrubs when collecting food and to some extent the blue color of the water.